Because of an influx of adware, Google has gotten rid of two Chrome extensions.
The extensions in question are Add to Feedly and Tweet This Page. At first they were pretty popular and actually useful, but then they started to bombard their users with ads. This also marks a trend in which developers of these small extensions and add-ons will sell their product, which sometimes takes very little time to make, and then the extensions have ads pumped through them.
The developer of Add to Feedly, Amit Agarwal, was sent an email with “a four-figure offer for something that had taken an hour to create,” he said on his blog. He decided to take the money and it wasn’t until later that he saw what was being done with the extension. “These aren’t regular banner ads,” he said. “These are invisible ads that work [in] the background and replace links.”
Since then, and thanks to articles published in Arstechnica and OMG! Chrome, Google has announced that it is changing its policies  when it comes to extensions. Unfortunately they won’t take place until the summer, but if you’re using extensions that start to bombard you with adware, definitely let Google know.